Conventionally, for mounting process of a semiconductor integrated circuit to a connection substrate, a tape carrier package structure, a chip on board structure and a chip on glass structure have been used. According to those structures, the space between the semiconductor substrate and the connection substrate are filled with a seal resin. For an electrode structure in such a mounting structure, a bump bonding structure using a bump electrode has been used. The bump electrode may be a metal bump electrode, such as a gold (Au) bump electrode, a solder electrode made of an alloy of lead (Pb) and tin (Sn), and the like.
Such a metal bump electrode is deformed plastically, and the alloy of Pb—Sn may be broken from its crystal surface. The difference of the thermal expansion coefficients between the semiconductor substrate and the connection substrate males some thermal stress in the electrode. Such thermal stress can be also made by the difference of the thermal expansion coefficients between the seal resin and the bump electrode itself. The thermal stress makes thermal fatigue in the electrode, and therefore the electrode may be broken in some cases. The semiconductor integrated circuit is metal-plated, then the metal plate is etched to form the bump electrode. In the semiconductor substrate, a region which is uncovered with a protection layer, such as a trimming circuit, may be seriously affected by the plating process and etching process. Such a conventional electrode structure does not have high enough reliability of electrical connection, because the surface of the semiconductor integrated circuit is not enough protected.